The present invention relates to energy storage and heat pump systems, and more particularly to chemical heat pump and storage systems employing sulfuric acid and water solutions as the heat transfer and storage media.
Currently usable energy resources and current energy utilization rates dictate a hiatus between resources and utilization that will occur sometime after the year 2000 unless alternate energy resources are developed and made commercially viable and current resources are conserved. Coal, oil shale, nuclear and solar power, and industrial waste heat are presently considered to be the major incompletely developed energy sources. Although coal, shale and nuclear power can be, in essence, stored and utilized upon demand, solar energy, off-peak utilization electrical energy, and industrial waste heat are abundant energy sources that are only cyclically available and in essence require storage. For example, when solar energy is available, typically the demand for energy is low. Conversely, when the peak demand occurs, especially in residential and commercial applications, solar energy is not available.
Electrical energy is one of the conversion forms of energy that is most readily available from all of the various aforementioned energy sources. However, electrical energy too is very difficult to store in a confined space and in an economical manner. About the only means of presently storing electrical energy is in chemical storage batteries. Such batteries are large, bulky and relatively inefficient in their storage capability. Thus, they have a very low storage density. Another means of storing energy is in the form of heat. Various means of storing heat have been tried, including the addition of heat to liquids and/or solids that are confined by insulated or noninsulated containers. Such storage means have included large water tanks and large rock beds to which heat is transferred and stored in the form of sensible heat. These prior art methods, however, require large volumes of storage space and are thus relatively inefficient because they have a low storage density.
It is one broad object of the present invention to provide a means for storing heat energy, and more particularly to provide means for storing heat energy in an economical, efficient and high-density manner. It is a further broad object of the present invention to provide a means for pumping heat from a low-temperature source to a higher temperature at which it can be utilized. It is a further object of the present invention to combine a means for storing energy and for pumping heat. It is a further object of the present invention to provide a chemical heat pump and energy storage systems that occupy very little space, that present very little risk of contamination of the environment surrounding the systems, that are economical and relatively efficient to operate, and that are capable of operating for many years without major service efforts.